1. Field of the Invention
The present invention relates to a refrigerator, and more particularly, to a refrigerator which can prevent deformation of an inner case caused by insulating material foaming.
2. Background of the Related Art
For a fresh storage of food, an inside temperature of a refrigerator should be kept below a certain temperature. Therefore, in order to conserve cold air formed in the refrigerator and cut off infiltration of an external heat into the refrigerator, insulating material is placed between an inner case and an outer case of the refrigerator during fabrication of the refrigerator. In general, polyurethane foam is used as an insulating material for the refrigerator. The polyurethane foam is a thermosetting resin formed by causing polyester or polyether type polyhydric alcohol and diisocyanic acid ester to make reaction under presence of catalyst, such as water to form polyurethane fiber, when the polyurethane become porous consisting of micrometer units of cells of carbon dioxide freed during the reaction process. In this instance, for accelerating foaming of the polyurethane, a foaming agent is added.
FIG. 1 illustrates section of a part of a refrigerator having a cold air duct(hereafter called as a sidewall duct) for flow of a cold air in the sidewall of the refrigerator from the sidewall toward a door, schematically. The part shows a connection part of the refrigerator sidewall SW having an inner case 2 and an outer case 8, and a door D. The sidewall duct 4 is inside of the sidewall SW. By the way, different from other parts of the refrigerator, such as a rear wall, an upper part, and the like, since the sidewall SW of the refrigerator has a relatively small gap W1 between the inner case 2 and the outer case 8, a gap W2 between the side duct and the inner case 2 is also relatively small. In general, the gap W2 between the side duct 4 and the inner case 2 is in a range of 10 mm. Of the unexplained parts, xe2x80x98Ixe2x80x99 denotes a cold air inlet for receiving the cold air from a refrigerating chamber duct(not shown), xe2x80x98Oxe2x80x99 denotes a cold air outlet for discharging the cold air toward the door xe2x80x98Dxe2x80x99, and xe2x80x98Gxe2x80x99 denotes a gasket for maintaining sealing between the refrigerator and the door.
FIG. 2 illustrates a section of a part the sidewall duct 4 is fitted between the inner case 2 and the outer case 8 of the refrigerator. As shown, the sidewall duct 4 has a rectangular section, and a rib 4a at a center thereof for preventing deformation of the sidewall duct 4 caused by foaming pressure during insulating material foaming. The gap W2 between the sidewall duct 4 and the inner case 2 should be in general relatively smaller than a gap W3 between the sidewall duct 4 and the outer case 8, because, as the insulating material between the inner case 2 and the outer case 8 can not cut off an external heat perfectly, there will be a heat loss from the cold air flowing through the sidewall duct 4 if the sidewall duct 4 is deviated toward the outer case 8 out of a preset range, i.e., the gap W3 between the sidewall duct 4 and the outer case 8 becomes narrower than a generally set gap. In the foregoing structure, for insulating the refrigerator, the foaming liquid 6 including the aforementioned foaming material is injected between the inner case 2 and the outer case 8 from one side of the refrigerator, as shown in FIG. 2. Then, the foaming liquid 6 filled between the inner case 2 and the outer case 8 make polyurethane reaction after lapse of a certain time to form foam. Such a foaming causes the polyurethane insulating material to increase its volume compared to the originally injected foaming liquid, to exert a foaming pressure toward the inner case 2.
However, the related art sidewall duct structure of the refrigerator has the following problems. Once the foaming liquid 6 is injected into the sidewall SW of the refrigerator, the foaming liquid flows to one side(to upward in FIG. 2). Since the gap W2 between the sidewall duct 4 and the inner case 2 is relatively smaller than the gap W3 between the sidewall duct 4 and the outer case 8, a flow speed of the foaming liquid 6 flowing through a space between the sidewall duct 4 and the inner case 2 is slower than the foaming liquid flowing through a space between the sidewall duct 4 and the outer case 8. Therefore, the foaming liquid 6 flowed the space between the sidewall duct 4 and the outer case 8 blocks the flow of the foaming liquid 6 in the space between the sidewall duct 4 and the inner case 2, that causes a density of the foaming liquid 6 filled in a space between the sidewall duct 4 and the inner case 2 to be higher than the same in the other part. As a result, the foaming liquid in the space between the sidewall duct 4 and the inner case 2 makes a late foaming in which a foaming liquid keeps foaming even after foaming of the foaming liquid in the other parts is completed. The late foaming builds up a pressure in the space between the sidewall duct 4 and the inner case 2, to deform the inner case 2 of plastic. As a result, as shown in FIG. 3, there is a protruded deformed portion 2a at a left side of the inner case 2.
Accordingly, the present invention is directed to a refrigerator that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a refrigerator which can prevent deformation of an inner case caused by foaming of an insulating material between the inner case and the outer case.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the refrigerator includes a cold air duct fitted in a space stuffed with an insulating material between an inner case and an outer case of the refrigerator having a triangular section in a part facing the inner case for preventing deformation of the inner case in foaming of the insulating material, thereby preventing deformation of the inner case caused by late foaming.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.